C#中using

using当执行完代码段立即调用实例的Dispose
例子：

public static bool MergeDiff(string ver1, string ver2, string diff){    try    {        using(var src = new FileStream(ver1, FileMode.Open, FileAccess.Read))        {            using(var dst = new FileStream(ver2, FileMode.CreateNew, FileAccess.Write))            {                using(var rd = new FileStream(diff, FileMode.Open, FileAccess.Read))                {                    bool r = MergeDiff(src, dst, rd);                    return r;                }            }        }    }    catch(System.Exception exp)    {        AppLog.Error("MergeDiff Failed : " + exp.ToString());        return false;    }}